In a typical cellular radio system, also referred to as a wireless communication system, user equipments, also known as mobile terminals and/or wireless terminals communicate via a Radio Access Network (RAN) to one or more core networks. The user equipments may be mobile stations or user equipment units such as mobile telephones also known as “cellular” telephones, and laptops with wireless capability, e.g., mobile termination, and thus may be, for example, portable, pocket, hand-held, computer-included, or car-mounted mobile devices which communicate voice and/or data with radio access network. The user equipments may also be referred to as terminals or a UE:s.
The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a Radio Base Station (RBS), which in some networks is also called “eNB”, “eNodeB”, “NodeB” or “B node”. A cell is a geographical area where radio coverage is provided by the radio base station equipment at a base station site. The base stations communicate over the air interface operating on radio frequencies with the user equipments within range of the base stations.
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system, which evolved from the Global System for Mobile Communications (GSM), and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology. UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using wideband code division multiple access for user equipment units (UEs). The Third Generation Partnership Project (3GPP) has undertaken to evolve further the UTRAN and GSM based radio access network technologies. In the end of 2008 the first release, Release 8, of the 3GPP Long Term Evolution (LTE) standard was finalized and the release 9 and 10 is currently going on.